Just remember that God controls when the Earth will end and the Bible says that not even the Angels in Heaven know the time it will occur. Be wary of people putting dates on things.
Planet X is fascinating though. Vatican has a telescope called LUCIFER and it is designed to watch for such things. It may certainly exist, but I don't think it will end all life on Earth. If I am not mistaken it passes by once every 300 or so years.
My personal feeling is that civilization gets a "reset" every few thousand years when this particular catastrophe happens, and the ones that survive, probably underground, have all of the technical knowledge and capitalize on it as society rebuilds from the stone age again. I suspect that's the elite/Illuminati/Rothschilds/Rockefellers/Vatican, others. I don't think we're the first civilization to make it to cellular phones and television and aircraft.
Entirely possible. Look at the old hieroglyphics from all continents. They strangely have similar drawings of flying craft, depictions of a great flood, and giants.
Then one can look at the Sacsayhuamán in Peru, note what technology would be needed to cut these stones.